1. Field of the Invention
The present invention relates to mobile vehicles and, more particularly, is directed to collapsible mobile robots capable of entry into a storage tank or other large area with constrained entry points and having various types of tooling operably attached thereto to preform various cleaning, inspecting, and material handling tasks therein.
2. Description of the Invention Background
Prior and current waste disposal practices have caused degradation of the environment throughout the world. In recent years, due to the alarming rate of environmental degradation particularly in the United States, a number of laws and regulations have been enacted that require industry not only to find better ways of handling and storing both hazardous and non-hazardous waste materials but also to clean and decontaminate existing storage and disposal sites.
Such laws and regulations have not been focused on one particular industrial segment but instead have been directed to a variety of industries ranging from the nuclear power industry to the chemical and petroleum industries. For example, petroleum refineries, chemical plants, petroleum and chemical stock farms typically have large cylindrical storage tanks that have diameters ranging from 20 feet to about 300 feet and heights that range from 50 to about 100 feet that contain a variety of different hazardous materials. Tanks such as those that leak hazardous materials are often the focus of the aforementioned environmental cleanup laws. Many of those laws and regulations require hazardous material contained in leaking or deteriorating below and above-ground storage tanks to be removed therefrom and transferred to proper containment devices without the further contamination of the environment.
The cleanup and extrication of such hazardous waste materials from storage tanks, however, is typically fraught with many problems. For example, depending upon the hazardous nature of the waste material contained within the tank, human entry therein is very limited and often prohibited. In addition, access to the interior of the tank is also often limited to a relatively small diameter pipe-riser or manway that extends into the tank also making human access into the interior of the tank impossible or impractical. As such, many known material handling devices cannot be used to remove the hazardous material because such devices are not sized properly nor remotely controllable.
In addition, due to the variation of material consistency often found in storage tanks, a variety of extrication apparatuses-and processes must be used to completely remove the bulk of the material from the tank. For example, often times a tank contains a combination of liquid, solid, and pasty material that must be removed therefrom.
Liquid hazardous waste material can simply be pumped from the storage tank to a proper containment device by a variety of known pumping arrangements. Such pumping methods, however, cannot extract solidified material from the tank. As such, depending upon the type of solid material to be removed, solvents may be pumped into the tank to dissolve and liquify the solid material so that it may be pumped therefrom. Also, water has been used to create a pumpable slurry of solid material that has been pulverized into particles that can be removed by the pump. However, it is undesirable to introduce liquid material into tanks that are already leaking because the weight of such material may accelerate the hazardous material leakage from the tank and would also add to the volume of material to be decontaminated and disposed of and thereby increase the costs associated with such cleanup procedures.
A variety of other apparatuses and methods have been developed for extracting solid and semi-solid hazardous materials from storage tanks. For example, one method involves positioning a backhoe-like machine on the top of the tank and extending the bucket thereof into the tank through the opening therein to remove the waste material. This method of hazardous waste extraction has limited utility, however, due to the frequent inability to completely reach the material located on the tank bottom and along the interior perimeter of the tank. In addition, this extraction method cannot be used for removal of materials from a weakened or deteriorating tank due to the tank's inability to support the weight of the backhoe-like apparatus.
Another prior method for removing materials from enclosed vessels involves the use of a gantry crane mounted above the tank opening. The crane has a clam-shell type waste extraction bucket suspended therefrom that is adapted to extend into the tank through the opening therein. That method, however, is typically expensive and, depending upon the location of the vessel opening, cannot be used to remove material located around the interior perimeter of the tank.
Another apparatus developed for cleaning the interior of a storage tank is disclosed in U.S. Pat. No. 4,817,653 to Krajicek et al. The mobile, remotely powered robot disclosed therein contains sprayer apparatus and is adapted to ride upon the floor of the tank. To use that apparatus, however, the tank must first be substantially emptied and a robot entryway must be provided through the side of the tank. The component parts of the robot are then passed through the entryway into the tank wherein they are reassembled and operated by personnel located within the tank. It is readily apparent that the Krajicek apparatus cannot be used to extract hazardous materials from tanks that are substantially full of hazardous materials until the material has been removed therefrom by other extraction means. That device is also ill-suited for use in tanks where, due to the nature of the material stored therein, human access is prohibited. In addition, the Krajicek apparatus could not be used to clean storage tanks that may be substantially weakened by providing therein an entryway large enough to permit the passage of the robot's components therethrough.
Other robots adapted to operate in hostile environments are also known. For example, U.S. Pat. No. 4,932,831 to White et al. and U.S. Pat. No. 5,022,812 to Coughlan et al. disclose track-propelled robots that can be operated from a remote location by means of a tether line that is attached to the robot. Those apparatuses, while somewhat compact, are not collapsible to the extent necessary to permit them to be entered into a tank through a small existing manway or pipe riser therein and re-expanded into a more stable configuration capable of moving within the tank and performing a variety of decontamination, inspection, and material handling tasks.
Collapsible track propelled vehicles, however, are known in the construction industry. For example, U.S. Pat. No. 3,820,616 to Juergens and U.S. Pat. No. 3,700,115 to Johnson et al. disclose expandable and collapsible mobile vehicle chassis. Those apparatuses utilize various types of linear actuating devices to vary the overall track width of the vehicle. Such devices, however, are ill-suited for use inside an enclosed tank where human access is prohibited mainly due to their large size even when the tracks are fully retracted. In particular, because those vehicles require power to operate their linear actuating devices to cause the chassis thereof to assume a collapsed position, they could not be collapsed to a configuration that could be retrieved through the tank opening if power was lost to the vehicle.
As such, there is a need for a collapsible mobile vehicle that can enter a storage tank or other area with constrained entry points and be operated by personnel located outside of the tank or operating area. There is another need for a mobile vehicle that can enter a storage tank through an opening therein in a collapsed configuration and, thereafter, be expanded to a more stable material handling configuration. There is yet another need for a mobile vehicle as described immediately above that can be retrieved from a tank when power has been lost to the vehicle. There is a further need for a mobile vehicle that is capable of traversing and handling waste materials having a variety of different consistencies ranging from liquids to solids. Still another need exists for a collapsible mobile robot that may be fabricated from a variety of standard parts at a relatively low cost.